A shock absorber is a device that is used to absorb a mechanical impact, or shock, sustained by a moving vehicle due to variations in road surface. To accomplish this, a typical shock absorber may include a dampening device, such as a hydraulic or pneumatic piston, to dampen or lessen the effect of jarring sustained by the moving vehicle. For example, one type of shock absorber may include two (2) tubes, one tube telescoping into the other. When associated with a vehicle suspension system, one end of the shock absorber is connected to one end of a vehicle suspension spring and the other end of the shock absorber is connected to the other end of the vehicle suspension spring.
Thus, in order for the vehicle suspension spring to expand, the spring must pull the shock absorber tube apart and in order for the vehicle suspension spring to contract, the spring must push the shock absorber tube together. The vehicle suspension springs and the shock absorbers are used in conjunction with each other to provide the vehicle operator with a more comfortable ride and to prevent the vehicle from becoming unstable. For example, as the tire of a moving vehicle encounters a hole in the road or a raised area in the road surface, the springs may accommodate the resultant shock generated by the impact. However, without a device to help absorb the shock of that impact, the vehicle suspension springs may shake the vehicle's frame excessively and violently. To prevent this, shock absorbers are used in conjunction with the vehicle suspension springs to restrain the motion of the springs.
As can be seen, if the shock absorber offers a large amount of resistance, the motion of the vehicle suspension spring will be effectively restrained. If the shock absorber offers a small amount of resistance, the motion of the vehicle suspension spring will be poorly restrained. Thus, by offering resistance to and by dampening the movement of the vehicle suspension spring, the shock absorber takes away, or absorbs', the movement of the spring and dissipates it as heat. This is typically accomplished by connecting the ends of the shock absorber to a piston in an oil-filled or oil and gas filled chamber disposed within the shock absorber's inner tube. Using this design, the shock absorber may expand and contract only if the piston forces oil and/or gas past it through valves in the shock absorber. This is accomplished by pulling and pushing on the ends of the shock absorber.
When the ends of the shock absorber are pushed together, the fluid and/or gas contained within the compression side of the cylinder is compressed. During this process, a small amount of fluid and/or gas is forced out of the compression side of the cylinder and into the rebound side of the cylinder. When the ends of the shock absorber are pulled apart, the fluid and/or gas contained within the rebound side of the cylinder is compressed forcing a small amount of fluid and/or gas out of the rebound side of the cylinder and into the compression side of the cylinder. This arrangement creates a large resistance to any motion by the piston and consequently by the ends of the shock absorber.
The Harley Davidson® SOFTAIL® motorcycle suspension system uses a swing arm that is pivotally attached to the struts of the motorcycle main frame. This allows the rear wheel assembly to move independently from the frame about a singular pivot axis. Thus, the swing arm rotates about a pivot and allows the wheel to move in an arcuate motion. The swing arm has a pair of wheel mounts that are positioned and spaced to mount a wheel assembly and provide proper orientation and location for the wheel relative to the motorcycle. The swing arm has a pair of supports at each wheel mount, wherein each pair are positioned in a plane and radiate from the wheel mount to a support member that connects the pair of supports in a planar like orientation. Transverse bars, or cross members link each of the wheel mounts to an upper location and a lower location providing proper spacing and structural rigidity for the swing arm. At an intermediate location, positioned between the upper and lower cross members, an additional transverse bar or cross member links each wheel mount. The intermediate cross member is tubular, and provides an axis for the swing arm to rotate about. Each of the support members has a hole that coincides with the tubular shaped cross member, providing a through-hole for pivot bolts to be inserted therethrough. Each support member is positioned adjacent to, and located inside the frame and is therefore hidden by the main frame struts, giving the illusion of a motorcycle having no visible suspension system.
The standard or stock SOFTAIL® motorcycles use a suspension system that incorporates two shock absorbers that are positioned in a parallel relationship to each other and are oriented so the longitudinal axis of the shock absorbers are parallel to the direction of travel of the motorcycle. One end of each of the shock absorbers is attached to the main frame. The other end of each of the shock absorbers is connected to a member that extends forward from the lower cross member of the swing arm. The main frame of the motorcycle hides the shock mounts from view, maintaining the appearance of the SOFTAIL® motorcycle.
Unfortunately, however, due to existing shock absorbers designs, current shock absorbers are not easily installed and when installed they are not easily adjustable.